Photochemistry and environment XIII: Phototransformation of 2-nitrophenol in aqueous solution

The photolysis of ortho-nitrophenols: a new gas phase source of HONO

“…In addition, abstraction of HONO was calculated to be energetically possible from a similar nitronic acid structure III of nitrobenzene, 35 and might also explain the HONO formation in the gas phase observed in the present study for the photolysis of nitrophenols. HONO formation was also observed during the photolysis of 2-nitrophenol in the liquid phase [22][23][24] and was explained, at least in part, by the elimination of HONO leading to an organic biradical. 23 To obtain further insight into the mechanism leading to HONO formation upon photolysis, the influence of the buffer gas was studied.…”

“…HONO formation was also observed during the photolysis of 2-nitrophenol in the liquid phase [22][23][24] and was explained, at least in part, by the elimination of HONO leading to an organic biradical. 23 To obtain further insight into the mechanism leading to HONO formation upon photolysis, the influence of the buffer gas was studied. From the different experiments in the absence of oxygen the following trend in the HONO yield was observed: HONO(He) 4 HONO(Ar) 4 HONO(N 2 ) (see Fig.…”

“…To explain the observed buffer gas dependency on the HONO yield it is proposed that the excited state III** can be additionally quenched by the buffer gas, the effectiveness of which will depend on the nature of the gas being used, see reaction (b). For the liquid phase, the formation of a biradical leading to the formation of a ketene was proposed to explain HONO formation during the irradiation of 2-nitrophenols 23 and might also be a co-product of HONO during the gas phase photolysis, see reaction (d) in mechanism (3). …”

“…35 Thus, photo-dissociation of 2-nitrophenol and its methylated derivatives via structure III and formation of HONO in the gas phase might also be possible, as observed in the liquid phase. [22][23][24] To date, no observations of nitrous acid formation from the gas phase photolysis of nitrophenols have been reported in the literature.…”

“…21 In contrast to the liquid phase, 11,[22][23][24] the photochemistry of nitrophenols in the gas phase has, to the best of our knowledge, received virtually no attention. Nitrophenols strongly absorb in the atmospherically relevant UV range 300-400 nm, 11,22,23 corresponding to the S 1 ' S 0 transition as reported for the liquid phase. 22 Thus, the photochemistry of nitrophenols might be of importance for the atmosphere.…”